Improvement of sol-gel prepared tungsten trioxide photoanodes upon doping with ytterbium

Abstract

Please cite this article as: Ana Korina Díaz-García, Roberto Gómez, Improvement of sol-gel prepared tungsten trioxide photoanodes upon doping with ytterbium, Journal of Photochemistry and Photobiology A: Chemistry https://doi. HIGHLIGHTS A sol-gel method for the preparation of Yb-doped WO3 photoanodes is presented. Ytterbium modification induces an increase in the photoresponse of WO3 electrodes. Yb changes WO3 morphology and surface charge without increasing carrier density. AbstractThe development of efficient and stable photoelectrodes keeps on being critical in the development of practical water splitting devices. Sol-gel synthesized tungsten trioxide thin film electrodes modified with ytterbium have been prepared on conducting glass substrates. All the obtained electrodes were found to be composed of monoclinic WO3, which is the photoactive crystal phase of WO3 for water oxidation. The photoelectrochemical behavior of both WO3 and WO3:Yb nanostructured electrodes in 0.1 M HClO4 is apparently characterized by a low degree of recombination. Ytterbium addition to tungsten trioxide improves its photoelectrochemical response as larger photocurrents are obtained without a significant change of the onset potential. This behavior is attributed primarily to a surface effect rather than on bulk doping. The addition of H2O2 to the aqueous electrolyte gives rise to both an increment in photocurrent and a shift of the photocurrent onset potential toward less positive values, which can be linked to the fact that hydrogen peroxide acts as an efficient hole scavenger. The implications of these findings in the mechanism of water photooxidation on WO3 are discussed.